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Testing Base Exception Handling and I18n Integration in Grape

This test suite validates the base exception handling functionality in Grape, focusing on message composition and I18n integration. It ensures proper error message formatting and localization behavior across different I18n configurations.

Test Coverage Overview

The test suite provides comprehensive coverage of Grape’s base exception class functionality:

Message handling and string conversion
I18n integration with different locale configurations
Fallback behavior for missing translations
Enforcement of available locales

Implementation Analysis

The tests employ RSpec’s behavior-driven development approach using subject/let patterns for clear test organization. The implementation focuses on three key areas: basic message handling, direct message access, and complex message composition with I18n integration.

Notable patterns include context-based test organization and shared setup/teardown using before/after hooks.

Technical Details

Testing Framework: RSpec
Key Components: I18n configuration management
Test Setup: Isolated I18n configuration per test
Mocking: I18n locale and enforcement settings

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Proper isolation of test cases
Comprehensive edge case coverage
Clean setup and teardown
Clear context separation
Effective use of RSpec’s expect syntax

ruby-grape/grape

spec/grape/exceptions/base_spec.rb

            
# frozen_string_literal: true

describe Grape::Exceptions::Base do
  describe '#to_s' do
    subject { described_class.new(message: message).to_s }

    let(:message) { 'a_message' }

    it { is_expected.to eq(message) }
  end

  describe '#message' do
    subject { described_class.new(message: message).message }

    let(:message) { 'a_message' }

    it { is_expected.to eq(message) }
  end

  describe '#compose_message' do
    subject { described_class.new.send(:compose_message, key, **attributes) }

    let(:key) { :invalid_formatter }
    let(:attributes) { { klass: String, to_format: 'xml' } }

    after do
      I18n.enforce_available_locales = true
      I18n.available_locales = %i[en]
      I18n.locale = :en
      I18n.default_locale = :en
      I18n.reload!
    end

    context 'when I18n enforces available locales' do
      before { I18n.enforce_available_locales = true }

      context 'when the fallback locale is available' do
        before do
          I18n.available_locales = %i[de en]
          I18n.default_locale = :de
        end

        it 'returns the translated message' do
          expect(subject).to eq('cannot convert String to xml')
        end
      end

      context 'when the fallback locale is not available' do
        before do
          I18n.available_locales = %i[de jp]
          I18n.locale = :de
          I18n.default_locale = :de
        end

        it 'returns the translation string' do
          expect(subject).to eq("grape.errors.messages.#{key}")
        end
      end
    end

    context 'when I18n does not enforce available locales' do
      before { I18n.enforce_available_locales = false }

      context 'when the fallback locale is available' do
        before { I18n.available_locales = %i[de en] }

        it 'returns the translated message' do
          expect(subject).to eq('cannot convert String to xml')
        end
      end

      context 'when the fallback locale is not available' do
        before { I18n.available_locales = %i[de jp] }

        it 'returns the translated message' do
          expect(subject).to eq('cannot convert String to xml')
        end
      end
    end
  end
end